Note that some of the remaining issues on this list are already marked "FIXED." The candidate fixes for those issues are not yet included in this release, but they will be included in a future Service Release or Feature Release.

Some higher-visibility known issues from the open bug list

[Xamarin for Visual Studio], [Xamarin Studio] - Upcoming compatibility feature, tracked in 44330 - "This version does not have support for files saved in Xcode 8 format" appears when attempting to edit a file with the Xamarin iOS designer after having edited the file with Xcode 8. Xcode 8 introduced a new, non-backwards-compatible XML format for Interface Builder documents that is not yet supported in Xamarin's iOS designer. As it turns out, Xcode 8.1 from Apple has in fact backed out of several of those format changes. Candidate fixes are now under test for Xamarin's iOS designer to cover the remaining format changes as present in Xcode 8.1.

[Xamarin Studio] - 43188 - Sporadic "Out of memory" error during build leaves solution in an unbuildable state until the project is reloaded.

Improved in this release: Cycle 8 Service Release 1 includes some fixes that should hopefully eliminate the need to reload the project in this scenario. Additional fixes for the "Out of memory" error itself are also planned.

Indicates also what last API Android version (25, 24, 23) it is possible to use without bugs.

It is also difficult to read points as :

It is essential to install the 32-bit version of the Java JDK even if you're using 64-bit Windows.

It is also important that v1.7 of the Java JDK is installed (although it is fine to have 1.8 or newer installed at the same time).

the last stable version of Xamarin Forms is 2.3.2.127 and the last stable versions of packages Xamarin.Android.Support.XXXX are 24.2.1 but if you install them, there is a bug, we need to install 23.3.0

Surprise, Surprise....... I t looks like to use the iOS Simulator in Windows you now must have Visual Studio Enterprise. I hope I am wrong but I noticed that when I did the latest upgrade to stable the check box to enable the iOS Simulator in Windows was no longer available. I then looked at the docs for the iOS Simulator for windows it now says Visual Studio Enterprise.
If this is true then this would be a terrible move on Xamarin's part. It could be the first step in clawing back free features to paid subscriptions.

Bug 45278 - VS2015: Any time the designer has been opened the next build hangs VS until I kill java.exe

The other note that might be relevant is to double-check that 64-bit Java JDK 8 (1.8) is installed and set as the active version under Tools > Options > Xamarin > Android Settings > Java Development Kit Location. There were some fixes around missing error messages for that scenario, but it's possible there might be some remaining edge cases that still show a loading indicator indefinitely rather than properly surfacing the error message.

This version sneaked out yesterday (I think there were two releases in the "stable" channel) breaks compiling against Forms 2.3.2 stable. Updating to 2.3.3. pre-4 fixes this. Version 4.2.1.60 for Visual Studio 2015.

Severity Code Description Project File Line Suppression State
Error Position 77:12. No property, bindable property, or event found for 'Height' AppName
Error Position 901:30. No property, bindable property, or event found for 'Width' AppName

I found a way to make the Android XAML designer work. Originally I could not open any XAML files. Then in solution explorer, I right clicked an Android layout xaml file and selected "Open with". This brought up a list of choices and I selected the default entry "Android Layout File" and then clicked the "Set as Default" button (despite the fact that it was already the default). I then exited Visual Studio and it started to work as it should do.

It is still a bit hit and miss, but when it fails now I usually restart visual studio and it fixes it.

Also, I have an Enterprise license but still have issues with the IOS Simulator for Wndows as pointed out in the earlier post (keep getting error Failed to install //Users/Username/Library/Caches/Xamarin/mtbs/builds/MyApp_IOS/c376935bf9404592497ac41462cd1465/bin/iPhoneSimulator/Debug/MyApp_IOS.app to 4D9D13A9-437F-4356-B21C-C0FA8D65B78C).

Does anyone know the reason why duplicate widgets appear in the Toolbar?
Possibly related question - when opening a layout in the designer I (sometimes) see a "Loading Layout" green progress bar and the layout never loads. I have to restart the VS to fix this. It all started right after I updated to the latest Xamarin (4.2.1.60)